docs: def state(self, filter_nodes=None, filter_routing_table=None,
                        filter_metadata=None, filter_blocks=None,
                        filter_indices=None):
          """
          Retrieve the :ref:`cluster state <es-guide-reference-api-admin-cluster-state>`.
  
          :param filter_nodes: set to **true** to filter out the **nodes** part
                               of the response.
          :param filter_routing_table: set to **true** to filter out the
                                       **routing_table** part of the response.
          :param filter_metadata: set to **true** to filter out the **metadata**
                                  part of the response.
          :param filter_blocks: set to **true** to filter out the **blocks**
                                part of the response.
          :param filter_indices: when not filtering metadata, a comma separated
                                 list of indices to include in the response.
  
          """
          path = make_path("_cluster", "state")
          parameters = {}
  
          if filter_nodes is not None:
              parameters['filter_nodes'] = filter_nodes
  
          if filter_routing_table is not None:
              parameters['filter_routing_table'] = filter_routing_table
  
          if filter_metadata is not None:
              parameters['filter_metadata'] = filter_metadata
  
          if filter_blocks is not None:
              parameters['filter_blocks'] = filter_blocks
  
          if filter_blocks is not None:
              if isinstance(filter_indices, six.string_types):
                  parameters['filter_indices'] = filter_indices
              else:
                  parameters['filter_indices'] = ",".join(filter_indices)
  
          return self.conn._send_request('GET', path, params=parameters)